ALBERT

Beschreibung: Tehran stands as one of the most earthquake-prone cities globally. This vast urban center, with a population exceeding 10 million, is intersected by several active faults in its vicinity, presenting significant seismic hazards. The occurrence of two Mw ~5 earthquakes in December 2017 near Malard and May 2020 near Damavand, further underscores the urgent need for comprehensive studies in the capital of Iran. Here, we primarily focus on the 2017 and 2020 seismic events and their causative faults. Additionally, we shed light on the limitations of Tehran's seismic monitoring and active faults map by addressing examples of unidentified seismic unrest and faults. By tackling the grand challenges of seismic studies and evaluating people's and cities' preparedness for a major earthquake, we draw insights from recent earthquakes around Tehran. Results show that the Malard and Damavand earthquakes occurred on the previously unknown and Mosha faults, respectively. Sparse seismic stations limit route detection thresholds and location accuracies of seismicity near Tehran. In addition, we show that the dispersion of population and distressed fabrics in Tehran is clustered, and the vulnerability to earthquakes is linked to physical and social factors. This study bears immense importance in enhancing seismological studies and risk reduction strategies for the Tehran province. Tehran stands as one of the most earthquake-prone cities globally. This vast urban center, with a population exceeding 10 million, is intersected by several active faults in its vicinity, presenting significant seismic hazards. The occurrence of two Mw ~5 earthquakes in December 2017 near Malard and May 2020 near Damavand, which resulted in the loss of life and significant consequences, further underscores the urgent need for comprehensive studies in the capital of Iran. Here, we primarily focus on the 2017 and 2020 seismic events and their causative faults. Additionally, we shed light on the limitations of Tehran's seismic monitoring and active faults map by addressing examples of unidentified seismic unrest and faults. By tackling the grand challenges of seismic studies and evaluating people's and cities' preparedness for a major earthquake, we draw insights from recent earthquakes and the 2023 Türkiye-Syria disaster. Results show that the Malard and Damavand earthquakes occurred on the hitherto unknown and Mosha faults, respectively. Sparse seismic stations limit route detection thresholds and location accuracies of seismicity near Tehran. In addition, we show that the dispersion of population and distressed fabrics in Tehran is clustered, and the vulnerability to earthquakes is linked to physical and social factors. This study bears immense importance in enhancing seismological studies and risk reduction strategies for the Tehran metropolis.

Beschreibung: A paradox exists between the great number of intermediate-depth earthquakes occurring along active subduction interfaces worldwide and the extreme scarcity of paleo-seismic events recorded in exhumed metasediments from ancient subducted slabs. Recrystallization associated with exhumation-related overprinting generally contributes to the nearly-complete erasing of markers of unstable slip events in metamorphic rocks. We herein focus on a sample from an ancient deep thrust from a Cretaceous High-Pressure paleo-accretionary complex in Chilean Patagonia. A representative, moderately foliated micaschist exhibits broken garnet crystals that host a dense network of healed micro-fractures. While garnet fragments appear thoroughly disaggregated along the main foliation, the rock matrix that completely recrystallized has lost the record of brittle deformation. We employ a 2D visco-elasto-plastic numerical modelling approach in order to investigate the mechanical conditions that enable the fracturing of isolated garnet grains in a relatively weak matrix. The rupture of these stiff grains is achieved in our models at strain rates faster than 10−10 /s to 10−12 /s for elevated pore fluid pressures (80 to 99 % of the lithostatic value, respectively). Since high pore fluid pressures prevail in deep subduction interface settings, it is suggested that the rupture of these garnet crystals occurred through cataclastic deformation via (transient) slip rate acceleration, perhaps as a consequence of localized slip associated with slow to conventional earthquakes. Upon slip rate deceleration, viscous disaggregation of the broken garnet clasts occurred along with the erasing of the matrix cataclastic fabric.

Beschreibung: In this study, we have incorporated tropospheric gradient observations from a Global Navigation Satellite Systems (GNSS) ground station network into the Weather Research and Forecasting (WRF) model through a newly developed observation operator. The experiments aim at testing the functionality of the developed observation operator and at analyzing the impact of tropospheric gradients on the sophisticated data assimilation (DA) system. The model was configured for a 0.1° mesh over Germany with 50 vertical levels up to 50 hPa. Our initial conditions were obtained from the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) data at 0.25° resolution, and conventional observations were obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF), restricted to mainly surface stations and radiosondes. We selected approximately 100 GNSS stations with high data quality and availability covering Germany. We performed DA every 6 h for June and July 2021. Four experiments were conducted: (1) a control run assimilating only conventional observations; (2) an impact run assimilating zenith total delays (ZTDs) on top of the control run; (3) an impact gradient run assimilating ZTDs and gradients on top of the control run; and (4) a gradient run assimilating only gradients on top of the control run. The error for the impact run was reduced by 32 % and 10 % for ZTDs and gradients, whereas the error for the impact gradient run was reduced by 35 % and 18 %, respectively. The gradient errors for the gradient run were nearly equal to those of the impact gradient. Overall, the newly developed operator for the WRFDA system works as intended. In particular, the combined assimilation of gradients and the ZTDs led to a notable improvement in the humidity field at altitudes above 2.5 km. With the operator codes developed and freely available to the WRF users, we aim to trigger further GNSS tropospheric gradient assimilation studies.

Beschreibung: Numerical models of subduction commonly use diffusion and dislocation creep laws from laboratory deformation experiments to determine the rheology of the lithosphere. The specific implementation of these laws varies from study to study, and the impacts of this variation on model behavior have not been thoroughly explored. We run simplified 2D numerical models of free subduction in SULEC, with viscoplastic slabs following (1) a diffusion creep law, (2) a dislocation creep law, and (3) both simultaneously, as well as several variations of model 3 with reduced resistance to bending. We compare the results of these models to a model with a constant-viscosity slab to determine the impact of the implementation of different lithospheric flow laws on subduction dynamics. In creep-governed models, higher subduction velocity causes a longer effective slab length, increasing slab pull and asthenospheric drag, which, in turn, affect subduction velocity. Numerical and analogue models implementing constant-viscosity slabs lack this feedback but still capture morphological patterns observed in more complex models. Dislocation creep is the primary deformation mechanism throughout the subducting lithosphere in our models. However, both diffusion creep and dislocation creep predict very high viscosities in the cold core of the slab. At the trench, the effective viscosity is lowered by plastic failure, rendering effective slab thickness the primary control on bending resistance and subduction velocity. However, at depth, plastic failure is not active, and the viscosity cap is reached in significant portions of the slab. The resulting high slab stiffness causes the subducting plate to curl under itself at the mantle transition zone, affecting patterns in subduction velocity, slab dip, and trench migration over time. Peierls creep and localized grain size reduction likely limit the stress and viscosity in the cores of real slabs. Numerical models implementing only power-law creep and neglecting Peierls creep are likely to overestimate the stiffness of subducting lithosphere, which may impact model results in a variety of respects.

Beschreibung: In dryland ecosystems, typically characterized by sparse vegetation and nutrient scarcity, pioneer plants exert a critical role in the build-up of soil carbon (C). Continuous root-derived C inputs, including rhizodeposition and structural root litter, create hotspots of increased microbial activity and nutrient availability where biogeochemical processes, such as soil aggregation and the accumulation and stabilization of organic matter (OM), are promoted. Our study aims to disentangle the effects of root C inputs on soil aggregate formation, microbial community structures, and on the fate of OM—both before and after plant death, i.e., during the transition from rhizosphere to detritusphere. This was realized in a two-phase incubation approach, tracing the natural and undisturbed transition from growth to subsequent decomposition of a pioneer plant-root system (Helenium aromaticum) in a semi-arid topsoil and subsoil. We quantified water-stable aggregates, investigated the fate and composition of OM separated into particulate and mineral-associated OM fractions (POM and MAOM), and observed successional changes in the root-associated microbiome. Our results underscore the significance of roots as vectors for macroaggregation within the rhizosphere in both topsoil and subsoil, associated with a particularly strong increase in fungal abundance in the subsoil. In topsoil, we identified root legacy effects in the detritusphere, as root-induced macroaggregation persisted after plant death, a phenomenon not observed in subsoil. These root legacy effects were accompanied by a clear succession towards gram + bacteria, which appeared to outcompete fungi during root decomposition. The increased availability of decaying litter surfaces further facilitated the protection of particulate OM via the occlusion into aggregates. Overall, to gain a holistic understanding of plant-microbe-soil interactions, we emphasize the need for more studies that span over the full temporal dimension from living to dying plants in intact soil systems.

Beschreibung: Integrating diverse expert opinions in hazard and risk projects is essential to managing subjective decisions and quantifying uncertainty to produce stable and trustworthy results. A structured procedure is necessary to organize the gathering of experts' opinions while ensuring transparency, accountability, and independence in judgements. We propose a novel Multiple-Expert management Protocol (MEP) to address this challenge, providing procedural guidelines for conducting single to multi-hazard risk analyses. MEP establishes a workflow to manage subjectivity rooted in (i) moderated and staged group interactions, (ii) trackable blind advice through written elicitations with mathematical aggregation, (iii) participatory independent review, (iv) close cooperation between scientific and managerial coordination, and (v) proper and comprehensive documentation. Originally developed for stress testing critical infrastructure, MEP is designed as a single, flexible, technology-neutral procedural workflow applicable to various sectors. Moreover, its scalability allows it to adapt from high to low-budget projects and from complex probabilistic multi-hazard risk assessments to standard single-hazard analyses, with different experts' degree and type of involvement depending on available funding and emerging controversies. We present two compelling case studies to showcase MEP's practical applicability: a multi-hazard risk analysis for a port infrastructure and a single-hazard regional tsunami hazard assessment.

Beschreibung: The Whole School Approach (WSA) is a concept aimed at holistically shaping educational institutions in the context of education for sustainable development (ESD), encompassing all aspects of the school environment. The focus is not only on the curriculum and teaching methods but also on creating a conducive learning environment, involving all school activities and facilities. A central element is the inclusion of the entire school community, including teachers, students, parents, custodians, canteen staff, and external partners. The concept has been established for many years and serves as a guiding principle in a number of schools. However, there is a lack of a method to quantify the success of implementing the WSA. This paper provides a basis for discussion to operationalise the WSA. For this purpose, a new approach was developed that includes the involvement of different actors and the implementation of specific climate protection measures (in teaching, energy saving measures in schools, promotion of renewable energies). The index score we developed is based on the allocation of evaluation points, which are useful for operationalising the WSA. Points are assigned in a clearly structured approach to make the results comparable. This new approach was tested with 12 German schools participating in the Schools4Future project (www.schools4future.de), confirming that the more diverse groups of stakeholders are involved, the more effective climate protection measures are implemented. However, it was also observed that key actors (especially students, teachers) can be largely responsible for a successful implementation of climate action measures.

Beschreibung: Background: National energy and climate scenarios are typically simulated or optimised using sectoral or energy system models, which include a large number of model settings and scenario assumptions. However, their realisation is contingent upon framework conditions and policy settings, which are often included in accompanying narrative scenarios. This paper therefore proposes refocussing the model-policy logic towards directly modelling policy effects. Applying this approach to the case of German passenger transport, I focus on demand-side policies and use open-source databases and models to develop a module for the translation of policies into model parameters. Results: Separate model runs were used to test a ceteris paribus policy reference scenario for 2035, the marginal impacts of modelled single policy effects, and a joint policy package scenario. Relative to the reference, demand-side policies show significant impacts: an annual reduction of 355 bn person-kilometres (30%) and a reduction of car-owning households from 95 to 90% in rural areas and from 76 to 64% in urban areas. The resulting mode shift decreases car-driven kilometres by 400 bn and increases public transport by 45 bn per year. This may reduce GHG emissions by an additional 30 Mt (or 33%) relative to the reference in 2035. Conclusions: Transport demand policies can significantly mitigate GHG, calling for a stronger policy focus beyond the much-studied shift to electric vehicles. While further research and model development are needed, the feasibility of policy scenario modelling increases its utility for policy-making.